Answer: Kim can mow the greens alone in 6 hours.
Step-by-step explanation:
Let K be the rate Kim mows the greens, and S the rate for Shayla. The rates K and S will be in greens/hour.
We know they can mow 1 green in 4 hours. We can state this as a sum of their rates times the 4 hours equals one green:
(4 hours)*(K + S) = 1 green
We are told that K = 2S [Kim is twice as fast as Shayla]
Subsititute:
(4 hours)*(K + S) = 1 green
(4 hours)*(2S + S) = 1 green
4*(2S + S) = 1 green
12S = 1 green
Shalya's rate is 1 green/12 hours
Kim is twice as fast: K = 2S
Kim's rate is 1 green/6 hours.
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Step-by-step explanation:
Answer:
Step-by-step explanation:
the probability that at least one envelope is a yellow envelope is 16/21
Step-by-step explanation:
The probability that at least one envelope is a yellow envelope is P(Y);
P(Y) = 1 - P(Y)'
P(Y)' is the probability that no envelope is a yellow envelope.
Given;
red envelope = 1
blue envelopes = 3
green envelopes = 2
yellow envelopes = 3
Total = 9
Number of non-yellow envelope = 9 -3 = 6(6 envelope are not yellow)
P(Y)' = P1 × P2 × P3
there is no replacement;
P(Y)' = 6/9 × 5/8 × 4/7
P(Y)' = 5/21
From equation 1;
P(Y) = 1 - 5/21
P(Y) = 16/21
the probability that at least one envelope is a yellow envelope is 16/21.
